When Can Kids Throw a Curveball?

Want to ignite baseball passions perhaps even more than a Yankee-Red Sox or Dodger-Giant rivalry?

Ask the question “When should young pitchers throw a curveball?” and then stand back.

The basic concern is that the still developing bone and soft tissue structures in the shoulder and elbow may not be able to adequately handle the rotational forces needed to throw a curveball. A wicked curveball thrown early in a career could potentially lead to wicked damage and early termination of said pitching career.

Do scientific studies and articles offer any substantial help?

The USA Baseball Medical and Safety Advisory Committee has the recommendation that a curveball should not be thrown until age 14, with only fastballs and change-ups thrown before this age.

Why age 14? Most likely because most pitchers at this age have nearly full if not complete maturity of growth centers around the elbow and shoulder and thus these joints can better handle the forces of throwing a curveball.

• Now, not every child develops at the same point, and in pediatrics we are often trained not to use an absolute age to determine maturity, but rather to use certain milestone to better gauge individual development.
• A pretty solid (and simple) recommendation that maintain this spirit comes from a Major League team physician who states “Don’t throw breaking pitches until you nave shaved".
• The age or development-based recommendations are primarily based on baseball expert opinion and have no significant evidence-based supporting data.

On the other hand, a systemic review of published studies by Grantham et. al in Sports Health concluded that limited biomechanical and most epidemiologic data do not indicate an increased risk of injury when compared with the fastball in pitchers from Little League through professional ranks.

• The epidemiologic evidence to support limitations on the curveball is lacking rigor in study design
• The current biomechanical evidence (kinematic and kinetic analysis of the torso, shoulder, elbow and wrist) does not support limiting the use of curveballs at any level of baseball

         However, before one rushes off to the local diamond to teach the curveball to young throwers, I must share some other important conclusions:

• A young pitcher has a wicked curveball very likely will be perceived as a better pitcher and thus be asked to throw more often, leading to higher pitch counts which have been shown to contribute to  arm overuse injuries.

o   In my experience, anything that makes a young pitcher stand out (taller than peers, good control, stronger fastball) put more pressure on coaches and families to protect those talents and not let them be overused at too young an age.

• The “over the top” wrist snap motion routinely used to increase curveball spin may overload certain forearm supinator muscles, so training these muscle groups along with the shoulder rotator cuff muscles for the curveball.

o   Share this opinion, and would also recommend addressing any limitations in shoulder internal rotation range of motion that can also overload the elbow and wrist regions.

•  Do not underestimate the often unsung virtues of the change-up pitch. The authors found two studies found that throwing a changeup pitch reduced the incidence of elbow and/or shoulder pain and voiced support for USA Baseball’s recommendations to use the change-up to prevent arm injuries.

My bottom line: use stage of development, not simple a specific age, to help determine when a child is ready to throw the curveball. Realize that a good curveball sets a kid up for being asked to pitch more frequently, which can lead to overuse. Assessing shoulder, elbow, and arm strength and range of motion can reduce risk of injury when throwing a curveball.

Sorting out Causes of Elbow Pain in Young Throwers

Any type of elbow discomfort in a young thrower is not a good thing, and while the easiest kids to worry about are those who will openly report elbow pain or limited motion, other more subtle signs of a potential elbow issue might be:

• "shaking" of the arm between throws
•  less interest in throwing
•  throws going higher than usual
•  not being as accurate with the location of throws.

I get particularly concerned about kids who can use a fingertip to identify the exact location of pain and those throwers who have swelling around the elbow joint. I'm also particularly careful with any case of limited ability to straighten the elbow compared to the non-throwing arm; while this might be more acceptable in an adult thrower, it definitely is not normal in a child or early teenage thrower.

Likely culprits leading to elbow pain can include excessive throwing both in one game and over the course of season(s), poor shoulder internal rotation, lack of strength in the legs and back, and trying to snap the wrist or straighten the elbow with too  much force after releasing the ball.

I'll list several common causes  by organizing them according to location within the elbow. Of course, this post is not intended to diagnose or treat any form of pain and should not be considered formal medical advice, but rather should be used as a guide to seek care from a qualified pediatric sports medicine specialist.

A few definitions:  INSIDE OF THE ELBOW is above the pinky side of the hand, and the OUTSIDE OF THE ELBOW is above the thumb side of the hand.

Keeping in mind the following visual about the unique forces that throwing places on the elbow can greatly simplify thinking about potential elbow injuries:

source: http://radsource.us/ulnar-collateral-ligament-tears-of-the-elbow/

• Structures on the INSIDE OF THE ELBOW (BLUE ARROWS) are stretched when a ball is thrown
• Structures on the OUTSIDE OF THE ELBOW (RED ARROWS) are compressed or pushed together when a ball is thrown

Inside (Medial) Elbow Pain (again, most often caused by that stretching motion)

• Irritation of growth plate (aka: medial apophysitis or "throwers's elbow")
  • he medial apophysis is a growth center separate from the rest of the humerus bone (upper part of elbow). Both ligaments (connect bones together) and tendons (connect muscle to bone) have attachment sites to the medial apophysis, so any stretch of these attachments can pull on the growth center and cause a range of injury from more simple irritation to a frank fracture and increased separation of the growth plate
• Irritation or strain of flexor/pronator  muscles
  • These muscles start on the inside of the elbow and allow snapping and/or rolling over of the wrist. Often can be injured after learning new breaking pitches or throwing too many breaking pitches with improper form
• Stretching of Ulnar Nerve
  • The ulnar nerve runs along the inside of the elbow and repetitive stretching can lead to damage with numbness and tingling sensations that travel down into the ring and pinky fingers.
• Ulnar Collateral Ligament (UCL) Tears
  • opularly known as the "Tommy John ligament", the typical story of a UCL tear is immediate pain after one throw with inability to continue throwing. Less common in throwers who haven't completed growth- the apophysis tends to be the weaker link. In more mature throwers (high school and above), the UCL is at greater risk of injury. 

Outside of the Elbow Pain (caused by compression)

• Capitellum Injury
  • ocated at the end of the humerus bone, the capitellum can be damaged by repetitive compression leading to either damage of the entire bone (usually in throwers age 5-10) or more local areas of bone and overlying soft tissue cartilage injury (usually in thrower over the age of 13).
• adial Head Injury
  • Also caused by repetitive compression, injuries to the radial head can involve damage to the growth plate that could affect long-term growth
• xtensor-supinator muscle injury
  • These muscles control straightening and rolling of the wrist. requently known as "tennis elbow", injuries to these muscles are much more common in adults and if suspected in a younger thrower, damage to the capitellum or radial head must first be excluded before making diagnosis of extensor-supinator muscle injury.

Back of the Elbow Pain

• Olecrenon impaction syndrome
  • Repetitive straightening (extension) of elbow can cause irritation of triceps muscle insertion into the olecranon, or even bone spur formation in the olecranon region. Often caused by trying to whip the arm into the straightened position with too much force.

No matter the location of pain, any possible elbow injury in a young thrower deserve urgent and specialized evaluation to determine exact cause, review contributing factors, and provide appropriate recommendations for treatment and recovery. Trying to throw through pain may lead to more damage and ultimately reduce future ability to return to throwing activities.